Glass is a hard, brittle and often transparent solid used, for example, in construction of windows, bottles, and lenses. Common types of glass include, but are not limited to soda-lime glass, borosilicate glass, boron and/or phosphorous doped glass, silicon dioxide, silicon nitride and aluminum oxynitride. Many types of glass contain silica as their main component. In many cases this oxide acts as a glass former which contributes to condensation to form a glass network.
Etching of glass has traditionally been performed by physical or chemical etching processes.
In previously available chemical etching processes, the surface to be etched is first covered with a mask of acid-resistant material forming a negative image, and then an uncovered portion of the surface defining the nascent positive image is exposed to an acid and ‘eaten away’, creating a desired etched pattern. Hydrofluoric acid (HF) is often used in chemical etching and provides a pattern with good abrasion resistance and durability.
In the physical etching process fine particles of sand are blasted against an unprotected portion of the surface to be decorated according to a mask. The sandblasting erodes the unmasked portion of the glass to produce a frosted appearance that provides a contrast for the untouched smooth transparent part of the glass. This process is lengthy and costly.
In some cases, screen printing is used to imitate an etched-appearance on glass. In screen printing, the etched appearance can be achieved by using etch imitation inks. In ink paste formulations for screen printing a combination of glass fits is used, in which a high melting frit is included. After firing a frosted appearance is produced by the high melting fits remaining on the surface. Screen printing is like chemical etching and physical etching in its reliance upon masks in the form of pre-prepared screens. The screens must be maintained and stored. Previously available screen printing inks are characterized by a narrow working temperature range that limits the utilization of etch imitation pattern in conjunction with other printing inks.
The three processes listed above all rely upon a mask that is removed after the action formation of the pattern. In many cases, the mask is formed by covering the entire substrate (e.g. with wax) and selectively removing solidified wax at places to be etched. In other cases, the mask is applied in a single step.
U.S. Pat. No. 5,594,044 describes an jet ink composition and a method for printing on glass, plastic, and metal surfaces messages having good adhesion and isopropyl alcohol rub resistance. The composition includes an organic solvent, a flexible thermoplastic urethane resin, a colorant, a cellulose nitrate resin, and an adhesion promoter.
U.S. Pat. No. 6,140,391 describes an jet ink composition suitable for application onto a substrate comprising an ink carrier, a colorant, a polyol, an aldehyde-based cross-linking agent, and a catalyst that promotes a reaction between the cross-linking agent, the polyol, and the substrate. In use, the composition is projected as a stream of ink droplets to a substrate with control of the direction of the droplets so that the droplets form the desired printed image on the substrate, and heating the image to obtain a cured printed image. Examples of preferred cross-linking agents are modified melamine formaldehyde resin and modified urea formaldehyde resin. The substrates preferably possess carboxyl, hydroxyl, amide, or sulfhydryl groups. An example of a preferred substrate is cellulose. The cross-linking reaction is carried out at relatively moderate temperatures and at high speeds. The printed image has excellent adhesion to substrates, abrasion resistance, crinkling resistance, water resistance, and heat resistance.
U.S. Pat. No. 6,156,384 and U.S. Pat. No. 6,616,981 describe a cationic, water-soluble polymer used as a substrate treatment resin (i.e., coating) to improve color-fastness and adhesion of an ink-jet ink printed onto the coated substrate. In one described formulation, a 50% solids aqueous solution of a cationic acrylic resin is provided as a substrate pre-treatment resin.
U.S. Pat. No. 7,029,110 describes a dispersion composition including a colorant and an acrylic polymer having a furan structure as well as an ink for an ink jet printer including the dispersion composition. The dispersion composition can achieve the satisfactory stability of the colorant irrespective of the kind of the colorant, and allows the inks to be formulated to have the same composition.
WO/2006/074791 describes a printable etching medium, with non-Newtonian flow properties for the etching of surfaces in the production of solar cells and the use thereof. The publication particularly relates to corresponding particle-containing compositions, by means of which the very selective fine structures can be etched without damaging or attacking adjacent surfaces.
WO/2008/052636 describes etching media containing particles in the form of etching pastes suitable for the full-surface, or selective etching of finest lines or structures in silicon surfaces and layers, and glass-like surfaces being formed of suitable silicon compounds. The publication also describes the use of the pastes for etching such surfaces.